Tears of Sanity
by niconiconyx
Summary: After a kidnapping that Shiro has carefully planned out and a new villain going overboard with her "test subject", Karma ends up mentally and physically broken. Will he lose all traces of hope and give in to despair, or will he let his friends- Nagisa in particular- heal him? And who is this assassin who has made it her goal to destroy the mind of everyone she fights?
1. Chapter 1: Break

**Heyo, my fellow potatoes! This is my first Assassination Classroom fanfiction, as you can see. :3 I'm quite new to this fandom, so feel free to correct me on any mistakes. XD Holy sh*t. This took long.**

 **I don't own Assassination Classroom or any of its characters, but I do own my OCs that is not going to take the spotlight unlike a lot of fan fictions. XD**

* * *

 **Nagisa**

It was just supposed to be another day. At least, that was how it had started out.

Then, it had quickly turned into a mass panic as _Hayami_ had been kidnapped in the night. We didn't know why it was her; but the brunette was strong. And, according to the little conversation I managed to have with Chiba, she _always_ slept with a gun under her pillow ever since she joined 3-E.

Of course, Koro-sensei was angry. So angry that everyone in class had shrunk back the moment we gave him the news. His face was pitch black, the colour of evil, and in those red eyes contained a bloodlust to _kill_ whoever had hurt his student. Seeing the normally easygoing, relaxed octopus-like creature turn to a destructive killing machine in mere seconds was enough to shake us all.

"Class is cancelled for today," was all he had said. Normally, such a notice would have us jumping in joy, but all we managed was a solemn nod. Even Karma was serious, his amber eyes fixed to his desk as he left the classroom quietly.

As our teacher went off- presumably to find Hayami- Chiba tapped him on the shoulder. He lifted his head, and for the first time, I saw a pair of worried red eyes glinting underneath his shaggy mop of black hair. He restlessly fingered his sniper as he spoke. "Can I come with you?"

I guess we all needed a little push to speak for what was right.

Minutes after Chiba had finished his sentence, we were all firmly grounded to our opinion- we _would_ go with Koro-sensei to save Hayami, no matter how dangerous it might be. Grudgingly, our teacher agreed, but on the condition that we wouldn't do anything stupid.

But, after all, being stupid was what Class E was famous for.

* * *

"Koro-sensei!" A robotic yet lively voice called through the thin glass screen of my phone. Why Ritsu had chosen mine today was unknown, but then again, she had always been a little unpredictable after being remodelled into a friendly member of our class. "We have an incoming message. It seems it's directing at you, Sensei."

Without waiting for anyone to speak, the digital image of Ritsu was replayed by a video. At first, it was eerily silent, and the camera never wobbled as it zoomed in on a bound Hayami. Her arms and legs were locked together with some type of metal handcuff, and a large, black piece of duct tape had been coarsely plastered over her mouth. Her blue eyes were as sharp and cold as ever, yet they pleaded with us to help her.

"Hayami…" I didn't need to look up from the screen to know that it was Chiba who had said it. There was then the echoing sound of footsteps, and everyone tensed up as they focused on the video. A man appeared onscreen, every part of him cloaked in white assassin's robe, save for the red eyes that glowered at us underneath his clothes.

" _Shiro,"_ we muttered collectively, having gathered a deep hatred for him after his many attempts at assassinating Koro-sensei, using Itona as nothing more than a tool before abandoning him, and robbing us of our chances to kill our teacher with our own hands and efforts.

I could feel his smirk digging into my heart underneath the swathed cloth that hid his mouth. "I assume you know this student I have here. Was her name Hayami Rinka?" He pretended to think for a while, probably to agitate Koro-sensei even further. "You octopus. I know you're watching this. Didn't you say no students would die on your watch?"

As Koro-sensei gritted his teeth, he continued. "A life for a life. This may seem different from our usual attempts, but if you want your beloved _student_ back, you have no choice but to come. Don't even try to send in your students; I assure you that we will take care of that quickly."

That was all he said before the screen flickered to black and to Ritsu gazing at us with a worried expression. "Is Hayami going to be alright, Koro-sensei?"

" _Yes."_ Ritsu shrunk back at the sharp tone, and Koro-sensei sucked in a sharp breath, before turning to us with his normal, innocuous face that seemed more than a little force. "He left an address, too. Come on; let's go."

* * *

"H-Hayami! Are you alright?" As soon as Chiba had caught side of the pigtailed brunette, he rushed over, ripping off the duct tape and and trying to unlock the cuffs. Finally, Itona stepped in, and with a glassy look, he quickly pushed around a few parts, causing the cuffs to fall out. Gasping, Hayami stood up, offering a slight, shaky smile to all of us. She seemed unscathed, except for a line of dark bruises on her neck.

Shiro stepped out from the entrance, still cloaked in white, and I tried hard not to lunge in for the kill. He was a master assassin, and despite everything that my friends and even Mr. Karasuma had said about my talent, he would probably be able to kill me swiftly.

Koro-sensei appeared before him, a jet black quickly sweeping across his form. His grin still stretched across his face, but it was more sinister, filled with malice and bloodlust. "Shiro. If I was just a _normal_ teacher, I would have gotten out of here before you had the chance to attack. Sadly, you have hurt my student, and for that, you will pay."

"Oh, Mr. Koro-sensei." Shiro let out an innocent chuckle. "I predicted that. You have gotten Hayami back with Itona's help, I see. Then you would stand nothing to lose if you beat me here, yes? Unfortunately, we have designed this to harm you either way." He clicked a button that had been cleverly concealed under a fold of cloth. "Akari, please tell me which student would be most useful as a test subject."

Before anyone could ask, a slim teenaged girl stepped out from behind the man.

Her hair was an extremely unusual colour- blue, purple and magenta pulsed through it like an alive galaxy, styled into two long locks that cascaded down her shoulders, as well a loose, short braid that kept her hair neat at the back. However, that wasn't the most unsettling feature about her.

The girl's eyes were a dark, bright magenta, glowing with the pure intent to kill. They kept on shifting from pink to red, and I couldn't tell what colour they were. Slowly, her eyes ran over all of us before she spoke.

"That one."

Before we could even discern who she was even talking about, Karma had been viciously thrown on the ground- all with the presumed Akari looking like she hadn't moved an inch. I gasped at the sighed, wanting to rush forward to help my friend up, but a chilling presence told me not to- that it would be suicide if I did. I could only stare at the shocked redhead lie on the ground, trying to determine what had happened.

"Karma-kun-" I started, but the redhead cut me off.

"It's fine, Nagisa-kun." Karma cut me off, but it lacked his usual easy confidence. I saw the hint of a painful-looking bruise starting to form at the base of his neck.

Akari pulled out two sharp blades out of nowhere, and as Karma got up, she ran towards him, slashing at him with her two knives, Karma, though flustered, easily dodged their hits. Itona stared at the ongoing fight with his usual empty expression, but I was _sure_ he was as concerned as everyone else. "It doesn't make sense. She doesn't have any tentacles, and her physical ability isn't especially outstanding," he commented.

"What the hell?" Karma gasped out as he was slammed into a wall, wincing at the impact. "How did she-" He stopped as the teenaged girl crossed her knives around his neck, cornering her opponent and preventing him from escaping. She made sure they grazed his neck, drawing at least a little blood, but it wasn't enough to do anything fatal.

I saw _Karma_ of all people falter at the twisted smile she suddenly possessed, her eyes now a bright, unmistakable flaming red.

"…It would be disappointing if I just killed you here." Akari finally spoke, and her sweet voice carried a dangerous, low undertone. "Y'know what? I like playing with my opponents a little before finally finishing them off. Mess with their minds a bit. And the sooner you give in, the less pain you suffer." She shrugged, a simple, relaxed action that carried such a deathly feeling. "It's when I hear their broken voice beg for mercy that I finally kill them."

Karma went in for another hit, but this time, everyone could clearly see the tactic she was using. Because surrounding him and stopping him from moving…

Was an aura of dark blue energy.

If I was in any other class, I wouldn't have dared to believe it. I would have brushed this off as a hallucination. But seeing Koro-sensei and all the other crap that had happened over the months, technology capable of giving someone the ability to use magic seemed plausible.

"Karma Akabane," She dragged out each syllable of his name, a torturous look in her burning eyes. "I know everything about you. And if you don't believe that…" another spectral flare of magic swirled absent-mindedly around her knife as she swiftly brought it to carve a line in his neck. "You should be experiencing a horrible memory right now."

As if on cue, Karma dropped to one knee, completely engulfed by her magic- or what seemed like it, anyway. His bright amber eyes had been dulled over by a dark, glassy look, stretched wide in horror and his usual innocuous smile had been replaced by an open-mouthed expression. A soft whimper escaped his mouth- something we had almost never heard from him.

"Oh, don't worry." I felt like throwing up as I head Akari speak again, her voice filled with false pity. "There's still so many more to go."

"Stop it…" I muttered, clenching my jaw. Koro-sensei tried to intervene, about to pick up Karma with the abnormal speed of his, but she didn't allow it. Almost instantly, a wall of energy shot up between us and the fighting duo.

"Want to know why I chose you, Karma- _kun_?" she asked, kicking him to the floor before he had any time to react. A smile stretched across her face, a tiny splatter of blood marring her pale face. It wasn't her blood- it was Karma's. "It's because you have the richest history out of anyone. I knew it. It would be a formidable test for me, indeed… but what's the fun in choosing an easy target?"

Shiro coughed. "Akari, you have done plenty. It's time to-"

"Just a _little_ more," she giggled out, stabbing at Karma once again. The knife hit its target, and Karma groaned out in pain as he looked weakly at the wound on his stomach. "Of course I'm aiming for physical damage as well, though," she told him. "You're going to be _beyond recognisable_ when I'm done with you."

Her eyes flickered once again, causing Karma to clutch his head in pain as what seemed like memories seemed to plague him, scene after scene, memory after memory. My mind wandered, wondering what _exactly_ the redhead had gone through in his life. He had never bothered to tell me, after all- and hearing what Akari had to say wasn't exactly helping…

"Hm. You're tough," she said, lunging at him once again. She disappeared under the protection of her blades, endlessly slashing at Karma. None of the wounds would cause him to die. but they were equally painful anyway.

 _At this rate, he'll pass out of blood loss soon…_

It felt like an eternity, but in reality, half an hour had passed by. We all knew that Karma had never stood a chance. He had withstood her onslaught of attacks, both physical and mental, but he was barely standing. Blood pooled around him, the same colour as his scarlet hair, and he looked blankly at Akari with a broken expression.

"You managed to endure it until the end!" A gracious smile formed on her face, one that twisted my heart. "But it seems like you've had enough. Tell me." She smirked, her red eyes glowing. "Get on your hands and knees. Tell me that you're nothing but a weak loser, and that you aren't able to do anything. _Beg."_ She had said that flawlessly with the same fake smile plastered on her face.

Karma stared at her emptily, and for a while, I wondered if he was going to rebel. However, in an almost robotic manner, he got into a kneeling position, and slumped as his head touched the ground. "I-" _Karma doesn't usually sound like that. He's strong, violent, manipulative-_ "I'm weak… I-I'm a loser… I-"

"Stop it!" I screamed at him, but he didn't seem to have heard me. " _KARMA!_ You're not like this!"

"I'm not able to do anything," he muttered, remaining in his bowed position.

"Good boy," Akari cooed, readying her knives in her hands as she held it above his head, ready to deliver the finishing blow. "Nice knowing you, Karma Akabane. Prepare to die." She grinned, and I launched myself at the barrier just as I had done this entire time. As usual, it was strong and unmoving.

"NO! KARMA!" I yelled, unable to watch this horrible, _horrible_ scene.

The hit never came.

Shiro had came to his senses, clicking yet another hidden button in his clothes. Groaning, the light in Akari's eyes blinked out as she fell to the ground, unmoving. Her chest still rise and fell, confirming that she was alive, but otherwise, she was unconscious.

"That's enough. It seems you're a tad bit more temperamental than I had planned for. Hmm… this bloodlust is a little too much…" He looked at the teenage girl's body.

Koro-sensei appeared by Karma's side instantly. The redhead's clothes were stained with a dark red, and his breaths were dangerously shallow. He had fallen unconscious, and I didn't know if he would be able to survive.

The octopus-like teacher scooped up his student as gently as he could, trying not to worsen any injuries. "Kidnapping one of my students and nearly killing another one." Koro-sensei's face turned black, but then reverted back to its original yellow. "I am unable to duel with you now because of Karma's state, but I will come back to _destroy you_ soon."

Then, sweeping all of us with him, he took off into the air at Mach 20 speed, hoping to get to the nearest hospital as quickly as possible.

However, my blood still ran cold. If Karma was alive… then his state wouldn't have worried me the most.

That hadn't been Karma at all.

Karma never begged for mercy.

* * *

 **SO, as you may wonder, if Nyxie-chan is evil enough to mentally and physically break her beloved Karma-kun, what else would she do? :3**

 **Critiques welcome and please review!**

 ***Salutes* Nyx out~! (^3^)7**


	2. Chapter 2: Transfer

**Reply to 2: I'M SORRY! I honestly forgot Kayano's actual name was Akari. Just know that my OC's name was changed to Ayaki, and I'll edit that into the first chapter as soon as I can!**

 **I don't own Assassination Classroom or it's characters, but I do own the plot and my OCs. Enjoy!**

* * *

 **Hospital in Japan, near Kunugigaoka Junior High School, Class 3E Campus**

 **Nagisa**

At _least,_ Koro-sensei let Mr. Karasuma do the talking this time.

If it was up to him, I was more than certain that the octopus would screw up in one way or another. Either his disguise would slip, his pent-up anger would lead him to kill someone, or he wouldn't be able to handle the hospital issues accordingly.

"Yes… I see. The Ministry of Defence will be handling all the bills. Thank you," The strict teacher's polite tone seemed forced, and with that, he turned away from his conversation with the doctor and walked back over to the group of concerned students. Immediately, I walked over to Mr. Karasuma, having to tilt my head up to stare at him straight in the eye.

"Is… is Karma-kun alright?" I asked, struggling to hide my concern. I had always thought of myself as a pretty good actor- after all, that was how I had managed to nearly assassinate Koro-sensei and Takaoka before by acting innocuous before quickly striking for that killing blow. But this… it didn't involve acting or assassination. When it came down to it, I was honestly just a regular, weak student that cared about his friends.

My teacher didn't say anything for a long while, trying to phrase his answer to not hurt me further. "He's in a coma," he finally stated, his hard black eyes softening at my expression. "He's sustained several serious injuries which led too excessive blood loss, as well as a broken wrist. They've stabilised his condition, but they don't know when he's going to wake up."

I was stunned into silence for a moment before replying. "Oh…" My voice was soft, and I didn't bother hiding the vulnerability in my tone.

"I'm sorry, Nagisa. I know you two are close friends, right?" Mr. Karasuma asked, his tone surprisingly gentle. I nodded wordlessly. "He's going to be fine. Karma's not the type to go down _that_ easily." He tried to keep his words light, but his face was solemn as usual.

"That wasn't Karma," I suddenly shot back, dropping the honorific for a moment. My voice was ice-cold. My fists clenched. "Didn't you see how that girl- Ayaki or something- broke him?"

There was another pause of silence before Koro-sensei spoke. I jumped, having forgotten about the teacher's presence- he'd been so quiet the entire time. "Right, class!" He announced in an unnervingly jovial voice. I could _tell_ that it was grim underneath. The smile on his face never went away. "I'm sure you're all very shaken about what happened today. Therefore, class is over for the rest of today. You can either go home to rest or remain here. Mr Karasuma will inform your parents." His gaze lingered on me for a second.

Slowly, my friends got up, their eyes more serious than usual. As Hayami passed by me, I noticed the ring of blue-black marks that spilled over the side of her neck. _Shiro's a sick-minded—_ "Are you OK, Hayami?" I asked quietly.

She nodded, stoic as usual. "Thanks for asking." Then, she disappeared out of the hospital, her fingers unconsciously reaching up to massage the injury that Shiro's men had inflicted.

Kayano- I didn't know if I should call her Akari- walked up. I tried to discern if she was acting or not, but I hoped that her concern was genuine. "You're staying here, right? Do you need me to-" I cut her off with a slight shake of my head. Kayano _was_ one of my closest friends- she had been extremely friendly with me since she had arrived, and I couldn't forget that moment of desperate shouting, when I had shouted at her that I never believed it was all an act- but this was different.

"I'm sorry, Kayano. I… I just want to be alone right now…" I trailed off. Kayano nodded, and she squeezed my hand slightly, as if to give me confidence, before slinging her bag over her shoulder and exiting. Looking at the now empty waiting room- everyone had understood I needed some time- I sighed. _Room 54._ That was were they were holding Karma.

The feeling of the cold metal on my hand was almost unwelcoming, as if steeling me mentally for what I was about to face. It was kind of ironic- I was able to keep my cool during the most nerve-wracking of assassinations, yet I was now feeling nervous at entering a hospital room.

 _Just go in,_ I shouted at myself, before gingerly turning the doorknob and walking in.

"Karma-kun?"

There was no answer. Then again, I didn't know why I had been expecting one. The redhead looked better than he did when Ayaki was tormenting him- the blood had been cleaned up as best as the doctors could, and his wounds had been tightly wrapped with several gauzy bandages. His right wrist hung limply by his side, badly broken, concealed and supported in a thick plaster cast.

His face was relaxed, his eyes lightly closed and his breathing shallow but even. He looked peaceful and relaxed- the complete opposite of the broken wreck that he had been this morning. The beeps from the heart monitor were the only sounds in the room. They were steady, but painfully slow.

He didn't belong in here. Karma was never so still and quiet- he was usually the energetic troublemaker of the class. Still, the thoughts that had ran through his mind, those memories- what _were_ they? Why did they hurt Karma so much?

Sunlight filtered into the room through an open window, the rays dancing on the unconscious boy's face, causing a golden hue to tint a few streaks of his crimson hair. His eyes flickered slightly in discomfort- either that, or it was a figment of my imagination. Still, I reached out to tug the blinds down, and a comforting dimness swept the light out.

I stared at the comatose figure blankly. The boy who usually towered over me with not just his height but his ominous presence looked so small and trapped, lying still and unmoving on the hospital bed.

"I'll _kill_ him," I muttered, and that threat seemed all too true. My mind was cluttered with hazy thoughts of bloodlust and murder, and the sinister meaning of that sentence screamed at me to make it come true- not just to kill, but to _destroy_ him.

"I'll kill Shiro, and I'll kill every single one of his workers."

* * *

 **The next morning, at the old campus for Class 3E**

Koro-sensei told us that we didn't need to come to class today if we didn't feel up to it, but in reality, it was

the only thing that could keep the matter off my mind. My mother had expressed concern for me when I came back, but didn't probe much otherwise.

"Good morning, class," he stated, his face pulled into his usual, wide grin. Numbly, I got to my feet, awaiting my teacher's command. "Class monitor, please issue the-"

"Class, stand," I muttered, even though everyone was already standing. "Aim." Usually, there would be several guns or knives aimed at the creature now, all poised and ready to attack. Today, everyone's hands were empty. "Bow and greet."

"Good morning, Koro-sensei."

He swiftly took attendance, purposefully starting from Isogai instead of Karma. Then, as we sat down, he started teaching, but not before slipping in a casual remark. "OK, class, we're having another transfer student in 3E today. She's a trained assassin, and that's all I know about her." We looked at each other, remembering how our previous experiences with Ritsu and Itona had been.

"It's a she," Kayano whispered to me. "What do you think she's like? Is she sent by… you know, Shiro?"

I shrugged, genuinely confused. We had been going through the year with no mishaps, and to suddenly have another student was unsettling. "She might be. Hell, she might even be Itona's replacement for all we know. Whoever she is, she's dangerous."

"Kayano! Nagisa!" Koro-sensei exclaimed, irritated. "Please do _not_ talk in class! You're interrupting the other students, and we would _all_ appreciate it if you kept quiet!"

We quietened down, turning to face the front of the classroom. Koro-sensei talked on and on about algebra- it was Maths first, after all- but nothing seemed to sink in. Usually, I was fine with algebra, but I just didn't feel _ready_ for class today. I was already regretting my decision.

"Nagisa?" Koro-sensei's voice shook me out of my trance. "Would you like to try solving this question?" Hiding a squeak, I bolted upright, my blurred vision suddenly clearing. Sure enough, an equation had been scrawled out on the blackboard with fading white chalk.

"Uh— I…" I trailed off, slowly walking up to the front and accepting the piece of chalk. I pressed it to the blackboard, but the more I stared at the line of complicated number, the more they were jumbled up in my mind. _It's too hard… and I wasn't listening earlier…_ I froze, trying to carefully piece apart the situation, but I _still_ couldn't solve it.

Koro-sensei shook his head, but he didn't look angry at all. "Please make an appointment to review this topic with me sometime, Nagisa. Algebra _is_ a vital part of the Maths syllabus."

I nodded and took my seat again, not speaking for the rest of the lesson- both because of a mix of concern and embarrassment.

* * *

 **End of recess time, morning**

The class shuffled back into the rundown building, waiting for Koro-sensei to arrive back from Italy. The teacher was, unsurprisingly, missing as usual- it had become so frequent that we had long been used to it. "I'm popping over to Italy for some pasta," he had informed us before taking off at his usual Mach 20 speed.

Soon enough, Koro-sensei landed back in Japan, barely avoiding crashing in from the window. Holding a still-steaming plate of pasta in his hands, he grinned at us. "Right! Chemistry now, isn't it?"

At that moment, there was a knock on the door. Koro-sensei lifted a tentacle and wrapped it around the doorknob. "Oh! It seems like the new student has arrived." He opened the door to see Mr. Karasuma with his arms folded, a stern expression on his fave as usual. At his side was a girl, her blue and magenta hair unnervingly familiar, tied up into a messy side ponytail.

"Ayame-chan, wasn't it?" The student nodded, but Koro-sensei's voice was strained with forced cheer. Then, as she turned to face the class, I suddenly knew _why_ exactly she had seemed so familiar. And it wasn't because of the strange hair colour that I had seen only yesterday.

No, it was something else completely.

Because, as her flaming red-magenta gaze burned into me, I _knew._

* * *

 **Cliffy because I can c:**

 **Replies to reviews:**

 **neko ouji: Yes, Shiro is very annoying ~ He's torturing everyone... Let's kill him together cx**

 **I12Bfree: I just realised what your name sounded like xD Yes, Karma-kun will eternally be tortured because I'm evil c: Thanks so much!**

 **Kasumi72: Ahh, thanks so much! I'm sorry if it's similar or anything; this idea came to me in a dream~ This really made my day!**

 **Critiques welcome and please review :) *salutes* Nyx out!**


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